The present invention relates generally to an apparatus for applying texture materials to wall and ceiling surfaces, and more particularly to an improved hopper gun with an internal air control valve for controlling the on and off function of the atomizing air stream and an integrated flow control valve to manage the volume/pressure ratio of the pressurized atomizing air. The air control valve and flow control valve integrated into the improved hopper gun provides improved control over the texturing process and simplified operation of the improved hopper gun.
Hopper guns are well known in the art. U.S. Pat. No. 4,863,104 to Masterson teaches a spray gun for applying ceiling acoustic textures using compressed air. A method is described therein where material to be sprayed onto a surface is gradually mixed with a compressed stream of fast moving air. A reservoir above the gun holds the material to be applied, and the material drains before a nozzle that emits forced air, entraining the mixture and the air in a stream that is delivered to the intended surface. The invention disclosed in the Masterson patent was an improvement over prior art in both efficiency and reliability. U.S. Pat. No. 5,979,797 to Castellano discloses a hopper gun wherein a low pressure air supply is used to spray the material and also to force material out of the hopper in a reliable manner. U.S. Pat. No. 5,393,034 to Mendez discloses an air valve for a hopper gun having a male quick disconnect air inlet fitting that feeds pressurized air into an inlet end of a longitudinal rearwardly movable trigger actuated air stem for propelling texture coating mixture and the like onto a surface to be coated. The air shut off valve comprises a tubular valve stem disposed within the air stream of the hopper gun such that an open first end of the valve stem lies within the male quick disconnect air fitting proximal to the inlet aperture of the fitting. The fitting has at least one air inlet port through a wall thereof proximal the first end thereof. The teachings of the Masterson, Castellano, and Mendez patents are incorporated by reference herein in furtherance of the understanding of the present invention.
The prior art can effectively apply the texture materials to the intended surface, but improvements are still possible to make the devices more reliable and more efficient. One problem that occurs in prior art hopper guns is that they are typically equipped with a peripherally disposed non-integrated ball valve for controlling the on/off function of the pressurized atomizing air. The ball valve is generally located below the handle of or behind the hopper gun and requires manual rotary actuation. This is generally not convenient for the operator.
Additionally, during setup for the application process the volume/pressure ratio of the pressurized atomizing air needs to be managed to assist in achieving a desired texture pattern. Prior art hopper guns also required the ball valve to perform a dual role. In addition to performing its primary function of starting and stopping the flow of pressurized atomizing air through the hopper gun, the ball valve is also used for controlling the volume/pressure ratio of pressurized atomizing air. This means volume/pressure has to be readjusted each time the pressurized atomizing air is shut off. Restarting the pressurized atomizing air involves an adjustment of the handle of the ball valve to some undefined intermediate position.
Having to continually adjust and readjust (for example when refilling the hopper) the volume/pressure ratio during the application process without any defined parameters leads to inconsistencies in the texture pattern produced by the hopper gun. The present invention seeks to overcome this problem by integrating a dedicated flow control valve into body of the hopper gun that controls the volume/pressure ratio produced by the hopper gun. This feature is exclusive of the on/off function for the pressurized atomizing air stream allowing it to be set one time at the beginning of the application process and left at that setting for the duration of the application process.